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Session 2. The Engineering Design Cycle in the Classroom
Objective. Turn a craft activity into a design challenge with measurable criteria and constraints, run it through ask, imagine, plan, create, test and improve in one or two lessons, and coach groups without rescuing them.
A design challenge can look like a craft lesson, and the difference is a number: a criterion that shows who succeeded and by how much. With it, pupils have a reason to test, to compare and to improve. Without it, the lesson ends with applause and nothing learned. This lesson goes deeper than the key ideas: it shows how to turn a wish into a criterion, how to run a fair test with a minimum of equipment and how to use failure as the most useful data in the room.
Key ideas
From a question to a problem
- Science asks why something happens. Engineering asks how we can make something work under limits. A STEM design task joins them: pupils use a science idea (shape and strength, insulation, filtering) to build something that must pass a test.
- Inquiry (course 8.3) answers 'what happens if ...?' about the world. Design answers 'how can we make this work?', and success is judged by a test against criteria, not by an explanation.
- A craft activity ('make a bridge') becomes engineering when there is a test and a chance to improve.
Criteria and constraints
- A criterion says what success looks like and can be measured: 'spans 20 cm and holds at least 10 coins'. If you cannot measure it, it is a wish, not a criterion.
- A constraint is a limit: 2 sheets of paper, 30 cm of tape, 15 minutes. Constraints make groups choose and make results comparable.
- Write both on the board before groups start, and give every group the same kit and the same test.
The cycle in 45 minutes, or in two lessons
- Ask, Imagine, Plan, Create, Test, Improve. Then repeat from Test. One 45-minute timing: ask and criteria 5, imagine and plan 7, create 13, test 8, improve, retest and share 12.
- With two lessons, build in the first and keep the models safe on a shelf. Test, improve and reflect in the second. Always keep a second try: without it, pupils learn only that they were right or wrong.
- Each group keeps a design log: sketch, prediction, test result, the ONE change made, new result.
Coach, do not rescue
- Ask 'how will you know it works?' and 'what will you change first?' instead of fixing the model yourself. Limit tape or time, not ideas.
- Praise improvement ('you went from 3 coins to 11') more than the first success. A failed test is data.
- After the test, name the science idea out loud (a folded sheet resists bending better than a flat one) and grade the design log and reasons, not the beauty of the model.
The engineering design cycle
From a wish to a criterion
Pupils say 'strong', 'cool' or 'good'. Ask 'how would we measure that?' and write a number: holds 10 coins, keeps water 3 degrees cooler, stands for 10 seconds. Choose one main criterion and, at most, one secondary one (for example, uses less than 30 cm of tape). Too many criteria make pupils guess what you want.
Then write the test in three lines so every group is tested the same way: what is used (identical coins), how (one at a time, in the middle), and when it counts as failed (the bridge sags to the table). Decide the safety of the test too: nothing heavy or sharp, a soft landing for anything that falls.
Failure as data, and how to grade it
Expect most first designs to fail the criterion. That is why the cycle repeats. When a model fails, ask three questions: What did you see? Where did it fail first? What is the one change you will try? Pupils who answer in this order are doing engineering thinking, and the model itself matters less.
To grade, use a three-line check: Did the design meet or approach the criterion? Do the reasons use the science idea? Did the group improve using evidence from its own test? The design log answers all three. Give the same kit to every group so results are fair, and keep the kit in a bag to save the minutes at the start of the lesson.
Examples from the classroom
Foil boats in Bukhara
Scene. Aziz gives Grade 5 groups a square of aluminium foil, 15 cm by 15 cm, and a basin of water. The criterion is to float as many coins as possible for one minute. First round: groups carry 12, 20 and 9 coins. The group with 9 had crumpled the foil. In round two they flatten the base and fold up wide edges: 31 coins. Same foil, different shape.
Insight. Shape, not extra material, can change performance, and a number makes the change visible.
The cup carrier
Scene. Jasur in Fergana asks Grade 6 groups to carry four cups of water 10 metres without spilling more than a finger's width of water from each. They have one sheet of card, 50 cm of string and 20 cm of tape. Round one: two groups spill half the water. After changing only the handle height, both groups keep the spill under the limit.
Insight. A tight constraint pushes groups to rethink the idea instead of adding more material.
The tower that fell
Scene. Dilnoza's Grade 6 in Samarkand builds paper towers to hold an apple 30 cm high for 10 seconds. One tower falls at 22 cm. She asks, 'What did you see? What will you change first?' The group notices that the base was narrower than the top. They widen the base and the tower holds the apple at 31 cm.
Insight. A short question after failure turns a collapsed model into evidence for the next step.
Common pitfalls
- Giving the task without any number to show success.
- Letting groups change several things at once, so they cannot say what worked.
- Grading the neatness of the model instead of the log and reasons.
- Rescuing a failing group with your own idea, which ends their learning.
Paper Bridge Challenge, Two Rounds
- Open the Activity Kit: design brief for a paper bridge (20 cm gap, 2 sheets, 30 cm tape, scissors). Groups of four with roles: builder, measurer, recorder, reporter (5 min).
- Groups (10 min): imagine two ideas on paper, choose one, build it. Write your prediction: how many coins?
- Test 1 (5 min): place identical coins one by one at the middle of the span until it fails. Record the count and what happened.
- Improve and Test 2 (10 min): change ONE thing, test again, record. Then use the sample results in the kit to decide which team learned most (5 min).
- Alone (5 min): write your classroom action task from the Kit.
Your facilitator will guide you through this activity in the session.
Questions to discuss
- Which change gave the biggest gain, and how do you know it was that change?
- Which constraint pushed you to a better idea?
- What science idea would you name after the test, and in which words?
Reflect
- Which craft activity in your textbook could become a design challenge by adding a test?
- How do you react when a group's model fails? What do pupils learn from that?
- What would you grade: the model, the log or the reasons?
Try it tomorrow
- Take one craft activity from the textbook and add a criterion, two constraints and a test.
- Prepare identical kits in bags for each group before the lesson.
- After the test, ask every group the three failure questions and listen for the science idea.
Further reading and links
A good design task has a measurable criterion, real constraints, a fair test and a second try.